Low-Power Long-Duration Versus High-Power Short-Duration Radiofrequency Ablation of the Atrioventricular Node.

BACKGROUND: Atrioventricular node (AVN) radiofrequency (RF) ablation is a highly effective treatment of atrial tachyarrhythmias that are resistant to other management modalities. To date, there is limited research that compares the properties of different RF ablation catheters. The current study aims to compare the effectiveness of several types of RF catheters in AVN ablation. METHODS: 66 patients, with a mean age of 73.27 years, underwent AVN RF ablation. The catheters used were categorized as: un-irrigated (UI), externally-irrigated (EI), and contact force-sensing with 10-20 grams of force. EI catheters were divided into two different settings: low-power long-duration (LPLD) (30W, 45°C, and 60 sec) and high-power short-duration (HPSD) (50W, 43°C, and 12 sec). We compared the success rate of the different RF catheters using logistic regression and lesion times using linear regression. RESULTS: The distribution of the types of catheters used is: UI in 48%, LPLD in 16%, and HPSD in 36% of patients. All ablation procedures were successful, with no immediate post-procedure complications. HPSD had a significantly shorter lesion time than UI catheters by 403.42 sec [-631.67, -175.17]. CONCLUSION: UI catheters, LPLD, and HPSD were equally safe and effective in ablation procedures. The HPSD catheter had a significantly shorter lesion time and, thus, overall decreased procedure time.

Comparative Effectiveness of Various Radiofrequency Ablation Catheters in the Ablation of Typical Atrial Flutter.

INTRODUCTION: Although ablation of typical atrial flutter (AFL) can be easily achieved with radiofrequency energy (RF), no studies compare the effectiveness of different ablation catheters. Our study aimed to compare the efficacy of various types of ablation catheters in treating typical AFL. METHODS: We analyzed patients with AFL who underwent RF ablation by a single operator at our institution. Successful ablation was evidenced by a bidirectional conduction block (trans-isthmus conduction time ≥ 130 ms or double potentials ≥ 90 ms). Logistic regression was used to compare success rate and linear regression to compare lesion time. RESULTS: Out of 222 patients, only six did not meet the success criteria (2.7%). The catheters used were non-irrigated, large-tip, internally irrigated (Chili II Boston Scientific), and externally irrigated (non-force-sensing) catheters (Cool Path, Abbott). An externally irrigated force-sensing catheter (TactiCath, Abbott) was used with > 10 gm of force and (LPLD) setting (30 W- 45 °C- 60 s), and high-power short-duration (HPSD) setting (50 W- 43 °C - 12 s). No complications were encountered. The catheter type had no statistically significant association with ablation success. With the use of externally irrigated catheter with contract force-sensing and HPSD settings, statistically significantly shortening of lesion time was achieved 758.3 s, [CI - 1128.29, - 388.35 s] followed by LPLD by 419.0 s [CI - 808.49, - 29.47 s]. CONCLUSIONS: The typical atrial flutter radiofrequency ablation procedure had a high success rate, which was not influenced by the type of ablation catheter. Contact force ablation catheter and HPSD are associated with shorter total lesion time.

Extremally rare cause of AV block during typical atrial flutter ablation not related to conduction tissue injury.

BACKGROUND: 51-year-old female with extensive prior atrial surgery involving myxoma resection and patch septum repair and prior typical atrial flutter as well as peripatch reentry underwent redo radiofrequency ablation of typical atrial flutter. METHODS: After high density mapping was performed, and gap in the prior typical flutter line was ablated. RESULT: During the ablation transient atrioventricular (AV) block was noted. Subsequent remapping of the right atrium revealed that there was a narrow strip of tissue between the cavo-tricuspid isthmus (CTI) and the coronary sinus (CS) os on which activation of the AV node was now depending. From all other directions, the AV node was surrounded by scar tissue. CONCLUSIONS: The most likely explanation for the transient AV block during the ablation procedure is that there was reversible injury to the tissue strip between the CTI and the CS os, which is critical for the activation of the AV node.

A Complete Workup of Recurrent Syncope Caused by Significant Left Main Coronary Artery Stenosis.

Syncope is usually caused by cerebral hypoperfusion. Differentials to consider during the workup of syncope includes vasovagal, orthostatic, drug-induced, arrhythmia, structural heart disease, and ischemic cardiomyopathy.  An 81-year-old African American man with recurrent witnessed syncopal events and newly diagnosed heart failure underwent extensive cardiac workup including electrocardiograms (EKG), echocardiogram, Holter monitor, electrophysiology (EP) study, and coronary angiogram. The workup revealed ischemic ventricular tachycardia in the setting of significant coronary artery disease including 80% distal left main disease. The patient underwent a coronary artery bypass graft (CABG) with subsequent resolution of further syncopal events. The patient was successfully discharged with guideline-directed medical therapy for heart failure with reduced ejection fraction (HFrEF) and coronary artery disease (CAD).  It is very rare for ischemic cardiomyopathy to present as syncope; however, it is not unheard of. Extensive transmural ischemia could lead to ventricular arrhythmias, a known cause of syncope. This rare presentation serves as a reminder to consider ischemic heart disease in the evaluation of syncope.

High-Degree Atrioventricular Block in a Patient With Asymptomatic COVID-19 Infection: A Case Report.

The first cases of COVID-19 infection were reported as pneumonia of unknown cause in China in December 2019. While respiratory complications remain the hallmark of the disease, multisystem involvement has been well documented. Cardiovascular involvement with potentially lethal myocarditis has been extensively reported in the literature. Reports of conduction system disturbances are much rarer, especially in patients without other signs of cardiac involvement. We present a case of an 88-year-old male with no prior cardiac history who presented to the hospital with obstipation. He was diagnosed with a small bowel obstruction and underwent a lysis of adhesions. During the hospitalization, he developed intermittent bradycardia with a high-degree atrioventricular (AV) block. A decision was made to implant a permanent pacemaker. During a pre-procedure COVID-19 screen, he was found to be positive for the presence of SARS-CoV-2 RNA. He had no signs of myocardial injury, a transthoracic echocardiogram showed no abnormalities, and he remained free of any respiratory symptoms. While the involvement of the cardiac conduction system has been documented in patients with symptomatic COVID-19 infection, our patient only exhibited conduction abnormalities and remained free of other COVID-19 symptoms. The sole involvement of the conduction system by COVID-19 is rare, especially in patients with otherwise asymptomatic infections. There is no long-term data to suggest whether such conduction abnormalities are temporary or permanent. As such, patients might benefit from the implantation of a permanent pacemaker.